Epidemiologic and mechanical studies suggest that cyclic loading (i.e., vibration) is an important etiologic risk factor in the development of degenerative disc disease. Posture, spinal stiffness, asymmetric spinal loading, and abdominal tone appear to influence the effect of vibration. Disability is more common in patients with certain personality traits. By analysis of a general practice population and questionnaire survey, we will define the role of cyclic loading in the broader perspective of low back pain (LBP). Sub-groups with and without back pain, with and without significant vibrational loadings will be identified. These sub-groups will then be investigated by questionnaire, and by standardized physical examination for spine stiffness, posture, straight leg raising, and neurologic abnormality, using developed Moire Fringe and vectorstereographic techniques. Psychologic factors will be evaluated by computerized modified Minnesota Multiphasic Personality Index (MMPI) and pain drawings. Objective radiographic analysis will correlate LBP with postural, congenital, disc space height and facet characteristics. The load deflection and impedance characteristics will be measured. By case studies, the environmental vibrational stresses, lifting requirements, and asymmetric loading configurations imposed on the spine will be analyzed. Safety recommendations will be given for vibrational loadings.